path: root/drivers/platform/surface/surface_dtx.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Surface Book (gen. 2 and later) detachment system (DTX) driver.
 *
 * Provides a user-space interface to properly handle clipboard/tablet
 * (containing screen and processor) detachment from the base of the device
 * (containing the keyboard and optionally a discrete GPU). Allows to
 * acknowledge (to speed things up), abort (e.g. in case the dGPU is still in
 * use), or request detachment via user-space.
 *
 * Copyright (C) 2019-2022 Maximilian Luz <luzmaximilian@gmail.com>
 */

#include <linux/fs.h>
#include <linux/input.h>
#include <linux/ioctl.h>
#include <linux/kernel.h>
#include <linux/kfifo.h>
#include <linux/kref.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/poll.h>
#include <linux/rwsem.h>
#include <linux/slab.h>
#include <linux/workqueue.h>

#include <linux/surface_aggregator/controller.h>
#include <linux/surface_aggregator/device.h>
#include <linux/surface_aggregator/dtx.h>


/* -- SSAM interface. ------------------------------------------------------- */

enum sam_event_cid_bas {
	SAM_EVENT_CID_DTX_CONNECTION			= 0x0c,
	SAM_EVENT_CID_DTX_REQUEST			= 0x0e,
	SAM_EVENT_CID_DTX_CANCEL			= 0x0f,
	SAM_EVENT_CID_DTX_LATCH_STATUS			= 0x11,
};

enum ssam_bas_base_state {
	SSAM_BAS_BASE_STATE_DETACH_SUCCESS		= 0x00,
	SSAM_BAS_BASE_STATE_ATTACHED			= 0x01,
	SSAM_BAS_BASE_STATE_NOT_FEASIBLE		= 0x02,
};

enum ssam_bas_latch_status {
	SSAM_BAS_LATCH_STATUS_CLOSED			= 0x00,
	SSAM_BAS_LATCH_STATUS_OPENED			= 0x01,
	SSAM_BAS_LATCH_STATUS_FAILED_TO_OPEN		= 0x02,
	SSAM_BAS_LATCH_STATUS_FAILED_TO_REMAIN_OPEN	= 0x03,
	SSAM_BAS_LATCH_STATUS_FAILED_TO_CLOSE		= 0x04,
};

enum ssam_bas_cancel_reason {
	SSAM_BAS_CANCEL_REASON_NOT_FEASIBLE		= 0x00,  /* Low battery. */
	SSAM_BAS_CANCEL_REASON_TIMEOUT			= 0x02,
	SSAM_BAS_CANCEL_REASON_FAILED_TO_OPEN		= 0x03,
	SSAM_BAS_CANCEL_REASON_FAILED_TO_REMAIN_OPEN	= 0x04,
	SSAM_BAS_CANCEL_REASON_FAILED_TO_CLOSE		= 0x05,
};

struct ssam_bas_base_info {
	u8 state;
	u8 base_id;
} __packed;

static_assert(sizeof(struct ssam_bas_base_info) == 2);

SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_lock, {
	.target_category = SSAM_SSH_TC_BAS,
	.target_id       = SSAM_SSH_TID_SAM,
	.command_id      = 0x06,
	.instance_id     = 0x00,
});

SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_unlock, {
	.target_category = SSAM_SSH_TC_BAS,
	.target_id       = SSAM_SSH_TID_SAM,
	.command_id      = 0x07,
	.instance_id     = 0x00,
});

SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_request, {
	.target_category = SSAM_SSH_TC_BAS,
	.target_id       = SSAM_SSH_TID_SAM,
	.command_id      = 0x08,
	.instance_id     = 0x00,
});

SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_confirm, {
	.target_category = SSAM_SSH_TC_BAS,
	.target_id       = SSAM_SSH_TID_SAM,
	.command_id      = 0x09,
	.instance_id     = 0x00,
});

SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_heartbeat, {
	.target_category = SSAM_SSH_TC_BAS,
	.target_id       = SSAM_SSH_TID_SAM,
	.command_id      = 0x0a,
	.instance_id     = 0x00,
});

SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_cancel, {
	.target_category = SSAM_SSH_TC_BAS,
	.target_id       = SSAM_SSH_TID_SAM,
	.command_id      = 0x0b,
	.instance_id     = 0x00,
});

SSAM_DEFINE_SYNC_REQUEST_R(ssam_bas_get_base, struct ssam_bas_base_info, {
	.target_category = SSAM_SSH_TC_BAS,
	.target_id       = SSAM_SSH_TID_SAM,
	.command_id      = 0x0c,
	.instance_id     = 0x00,
});

SSAM_DEFINE_SYNC_REQUEST_R(ssam_bas_get_device_mode, u8, {
	.target_category = SSAM_SSH_TC_BAS,
	.target_id       = SSAM_SSH_TID_SAM,
	.command_id      = 0x0d,
	.instance_id     = 0x00,
});

SSAM_DEFINE_SYNC_REQUEST_R(